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Punctuation: Colons

Colon Basics

Colons are punctuation marks used to separate parts of sentences. Use a colon in the following instances.

1. To introduce elements of a list. When the elements of a series do not fit naturally into a sentence's construction, use a colon to introduce them.

Example:The study's population consisted of the following groups: students, faculty, and staff.
Example:  The study's population consisted of students, faculty, and staff.

Note that in the second example, no colon was required.

2. To elaborate on a statement. Use a colon when employing an introductory clause with a final phrase that elaborates on the preceding thought.

Example: The sports writers agreed: The suspension was fair.

Note that the word The is capitalized because the clause that follows the colon is independent.

3. To introduce a block quotation. Use a colon when introducing a block quotation with an independent clause.

Example: Hemingway (as cited in Austin, 1976) insisted that a writer should always challenge him or herself:

For a true writer, each book should be a new beginning where he tries again for something that is beyond attainment. He should always try for something that has never been done or that others have tried and failed. Then sometimes, with great luck, he will succeed. (p. 43)

Note that there is no colon when introducing a block quote with a dependent clause.

Example: Hemingway (as cited in Austin, 1976) claimed that

Each book should be a new beginning where [the author] tries again for something that is beyond attainment. He should always try for something that has never been done or that others have tried and failed. Then sometimes, with great luck, he will succeed. (p. 43)

For more information on colon usage, see section 4.05 of the APA manual.